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Yr 2 - Control > Muscle Weakness > Flashcards

Muscle Weakness Flashcards

1
Q

Upper and lower motor neurons diagram

A
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2
Q

Examples of causes of muscle weakness:

A
  • Upper motor neuron; stroke, tumour etc
  • Lower motor neuron; (motor neurone disease, root damage, peripheral neuropathy, single nerve damage)
  • Neuromuscular junction; myasthenia
  • Muscle fibre; myopathy
  • Non-specific; systemic illness
  • Functional; poor effort, pain, hysteria, malingering)
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3
Q

Causes of UMN disorders?

A

Stroke, infection, tumour, degeneration

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4
Q

Where is the likely lesion if weakness is on;

a) one side of body
b) all 4 limbs
c) both legs
d) one limb

A

a) cerebral hemisphere
b) high cervical spinal cord
c) low cervical spinal cord
d) spinal root or peripheral nerve

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5
Q

Compare the:

a) muscle tone
b) reflexes
c) plantar response

in UMN vs LMN weakness

A

a) UMN: muscle tone increased (stiffer), LMN: decreased muscle tone (flaccid)
b) UMN: reflexes brisker/exaggerated, LMN: reflexes absent or depressed
c) UMN: plantars upgoing, LMN plantars downgoing

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6
Q

Examples of different groups of LMN disorders:

A
  • Neuromuscular Junction pathology
  • Muscle fibre pathology
  • Focal Nerve Pathology (single nerve)
  • Polyneuropathy (two or more nerves)
  • Generalised peripheral neuropathy
  • Root Pathology (radiculopathy)
  • Motor Neuron Disease (can be UMN and LMN)
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7
Q

Neuropathic lesions can be divided into 2 categories. What are these?

A
  1. Axonal loss
  2. Demyelination
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8
Q

What is the most common neuromuscular junction disorder?

A

myasthenia gravis

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9
Q

Symptoms of myasthenia gravis / NMJ disorders?

A
  • Proximal weakness
  • Fatigability
  • Worse as the day goes by
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10
Q

Describe the

a) sensation
b) reflexes

in NMJ disorders. Why?

A

a) normal
b) normal

are LMN disorders

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11
Q

What test is used to diagnose NMJ disorders?

A

Repetitive nerve stimulation (RNS)

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12
Q

What is Repetitive nerve stimulation (RNS)?

A

Electrical stimulation is delivered to a motor nerve repeatedly several times per second. Observing the change in the muscle electrical response (CMAP) after several stimulations, a physician can assess for the presence of an NMJ disease and differentiate between presynaptic and postsynaptic condition

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13
Q

What is the result of RNS in an NMJ disorder?

A

A decremental response (a smaller and smaller muscle response with each repetitive stimulus) is abnormal and indicates NMJ dysfunction)

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14
Q

What does a decremental response in an RNS indicate?

A

NMJ disorder

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15
Q

What are 2 major types of muscle fibre pathology?

A
  1. Myopathy
  2. Myositis
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16
Q

What is myositis?

A

any condition causing inflammation in muscles

17
Q

What is myopathy?

A

a disease of the muscle in which the muscle fibers do not function properly, resulting in muscular weakness

18
Q

Signs and symptoms of muscle fibre pathology?

A
  • Progressive weakness (rapid or slow)
  • Usually presents in proximal muscle groups first
  • Normal sensation, reflexes, tone
  • Moderate wasting
19
Q

Describe the

a) tone
b) reflexes
c) sensation

in muscle fibre pathlogy?

A

a) normal
b) normal
c) normal

as is a LMN disorder

20
Q

What is focal nerve pathology?

A

Damage to a single nerve e.g. carpal tunnel syndrome

21
Q

Symptoms of carpal tunnel syndrome?

A
  • Pain in hand and wrist
  • Pain occurs when the wrist is bent
  • Pain is worse at night
  • Aggravation of symptoms happens when the hand is bent forward
  • Numbness and tingling sensation in hand especially in the thumb, index middle and ring finger
  • Weakness of hands
  • A shock-like sensation is felt
22
Q

What is polyneuropathy?

A

Polyneuropathy is when multiple peripheral nerves become damaged, which is also commonly called peripheral neuropathy.

23
Q

What is the msot common cause of polyneuropathy?

A

Diabetes

24
Q

What is radiculopathy?

A
  • Radiculopathy describes a range of symptoms produced by the pinching of a nerve root in the spinal column (cervical, thoracic or lumbar).
  • Symptoms of radiculopathy vary by location but frequently include pain, weakness, numbness and tingling
25
Q

What is motor neuron disease?

A
  • Disease of motor neurons (UMN & LMN)
  • Progressive motor deficit
  • Peak age 50-70
  • Can be as young as 20, and much older
26
Q

Aetiology of motor neuron disease?

A
  • Cells in the CNS and PNS start dying (cellular apoptosis via lysosome digestion)
  • Causes:
    • Progressive, unknown (idiopathic)
    • Sporadic
    • 5-10% of cases genetic cause
    • Toxins, viruses, trauma, combination
27
Q

Symptoms and signs of motor neuron disease?

A
  • Painless
  • No loss of feeling
  • Progressive bulbar palsy: weakness in the tongue, face and palate leading to dysphasia, dysarthria, nasal regurgitation and aspiration
  • Normal cognition
28
Q

Life expectancy after MDN diagnosis?

A

3-5 years

29
Q

Functions that are preserved in MDN?

A
  • Eye muscles
  • Sphincters
  • Sexual activity
30
Q

There are 2 main forms of electrodiagnostic assessments to assess the function of muscles and nerves. What are these?

A
  1. Nerve Conduction Studies (NCS)
  2. Needle Electromyography (EMG)
31
Q

What is a Nerve Conduction Study (NCS)?

A

Uses electrode stickers applied to skin (surface electrodes) to measure speed and strength of signals; sensory and motor assessment

  1. Sensory assessment;
    1. During the test, your nerve is stimulated, usually with electrode patches attached to your skin.
    2. measures how fast an electrical impulse moves through your nerve; can detect nerve damage
  2. Motor assessment:
    1. Stimulate motor nerve
    2. Record amplitude, size, shape of response; recording the compound muscle action potential (CMAP)
    3. Will give information about how many axons are available
    4. Gives information about myelination
32
Q

What is Needle Electromyography (EMG)?

A

Needle electrode inserted directly into a muscle records the electrical activity in that muscle

33
Q

What are the 2 earliest manifestations of axonal denervation that can be seen in an EMG?

A

The presence of positive sharp waves and fibrillation potentials.

34
Q

What are fibrillation potentials?

A

spontaneous action potentials generated by recently denervated muscle fibres; often triggered by needle insertion

35
Q

What are positive sharp waves?

A

another early manifestation of axonal denervation

36
Q

What is a motor unit?

A

a motor unit is the number of muscle fibres supplied by a single motor neuron

37
Q

What is a motor unit action potential (MUAP)?

A

EMG –> The representation of the changes generated by a MU is the so called motor unit action potential (MUAP).

Yr 2 - Control (71 decks)

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